1. Field of the Invention
This invention relates generally to inspecting fiber optic endfaces using video microscopes. More particularly, the invention relates to a fiber optic endface inspector having capabilities of wireless communication between its video microscope and its display device for transmitting video streaming signal of the endface image, and focus detection and automatic capture/analysis of focused image of the endface inspected.
2. Description of the Related Art
Dirt, dust and other contaminants are enemies of high-speed data transmission over optical fiber. Today's network applications require more bandwidth, making loss budgets tighter than ever. It is critical that all optical connections are clean and free of contaminants to ensure success of the applications. In the art of fiber optic endface inspection, video microscopes have been widely adopted as the primary tool in current fiber optic system installation and troubleshooting routines.
Available fiber optic video inspection microscopes in today's market are mainly in two categories; bench-top and hand-held, as shown in FIG. 1A and FIG. 1B, respectively. FIG. 1A illustrates that the bench-top microscope 11 is mostly connected to a computer 12 via a cable 13 to inspect free fiber ends (i.e. male ends), for example, the endfaces of fiber patch cords. Using a computer program, operators can watch, capture, and save fiber images. But this type of microscopes is not suitable for field or central office uses, where both male and female (in-adapter) ends need to be inspected and most of the ends cannot be moved or removed. Thus, hand-held inspectors have become the choice for installers or maintenance technicians who work at fiber optic CO/HE, FTTX networks, or fiber sensing networks.
As illustrated in FIG. 1B, a hand-held video inspector includes two primary parts: a microscope probe 14 and a display unit 15. The display unit 15 can be a simple LCD screen, an OTDR device, a smart phone, a tablet or a PC. The microscope probe 14 and the display unit 15 are connected via a long electrical cable 16. As the first primary part, the microscope probe 14 is typically a compact and ergonomic hand tool that allows the operator to easily access locales that are a little distant away or difficult to access. With this flexibility, instead of bringing a connector to the microscope, which often is not feasible or possible, a hand-held video inspector can work with connectors that are affixed in a position and not movable. Most ‘female’ connectors belong to this category. With specially designed adapting tips for the hand-held video inspector probe, not only male connectors but also female connectors can be easily accessed and inspected. As different adapting tips should be mounted onto the microscope probe for interfacing with different connectors, manufacturers of hand-held video inspectors often offer a large family of adapting tips, with different ferrule sizes, different polishes (AC or APC), and different genders (male or female). As the second primary part, the display unit 15 receives the video signal from the microscope probe 14 and displays the fiber endface images on its screen. If the display unit 15 possesses a microprocessor inside, e.g. in an OTDR device, smart phone, or tablet/PC, the images can even be processed and saved. As a physically separate unit from the microscope probe 14, the display unit 15 can be positioned not only a little distant from the connector position but also set at any favorite viewing angle.
Among commercial hand-held video inspectors, in order to allow a long reach of the microscope probe, the cable between the microscope probe and the display is typically at least 1.5 meters long. Such a cable connection often causes inconveniences to the operators, especially when they work in a crowded environment (e.g. around a densely distributed connector panel) or an awkward position (e.g. in aircraft or shipboard applications). Therefore, a wireless communication between the microscope probe and the display unit will eliminate the drawbacks of the wired fiber optic endface inspector mentioned above and enable the operator to work more efficiently.
The U.S. Patent Application Publication by Levin et al, US 2011/0085159 A1, proposed a fiber optic connector endface inspection probe that comprises a wireless transceiver. But the wireless function of their proposed probe is just sending saved images (photos) to a remote image viewing device. Under its ‘blind’ working condition (i.e. without a real time video monitoring in front of the operator), a built-in autofocus system has to be provided in this proposal. The elements in their autofocus system include a microprocessor, an electronics module and a motor with controller, and are responsible for image contrast analysis, focusing status judgment, and then sending driving signal to the motor for lens position adjustments. Other than these elements, the proposed probe should also enclose a wireless transceiver, a battery, and a memory card. As a result, this probe becomes fairly bulky, heavy and impractical. As an alternative, instead of autofocus, Levin et al also proposed a manually focusing approach. But in that approach a viewing screen and thus a higher battery power have to be built in, so that the probe ends up even bulkier and heavier.
In view of the drawbacks and deficiencies of the fiber optic endface inspectors currently available in the industry, there is an urgent need for improvements on fiber optic endface inspectors to make the task of endface inspection easier and less time-consuming.